Terminal for circuit assembly having a cradle portion to prevent tottering of the terminal

ABSTRACT

A terminal attachment structure includes a circuit assembly and a terminal attached to the circuit assembly. The circuit assembly has an insulating substrate and a circuit printed on the insulating substrate. The terminal is composed of a circuit-contact part, a connecting part to be connected with a mating terminal and a cradle part arranged between the circuit-contact part and the connecting part. When a force directing the insulating substrate is applied on the connecting part, the cradle part operates to receive the force. Accordingly, the circuit-contact part does not rise from the insulating substrate, so that clattering of the terminal against the circuit assembly can be prevented.

This is a division of application Ser. No. 08/821,449, filed Mar. 21,1997, now U.S. Pat. No. 5,945,637, which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a terminal to be attached to a circuitassembly comprising an insulating substrate on which a circuit isprinted and it relates to a terminal attachment structure which makes itpossible to attach the terminal to the circuit assembly.

Japanese Utility Model Publication (kokai) No. 4-6172 discloses oneexample of the conventional lead terminal attached to a substrate inorder to connect a circuit on the substrate with a lead. The leadterminal has a columnar pin part formed on one side thereof, a leadterminal part formed on the other side and a fit part arranged betweenthe pin part and the lead terminal part. The lead terminal part isprovided with a V-shaped groove defined by opposing pointed edges. Infitting, by inserting a lead into the groove under pressure, aninsulating cover of the lead is peeled by the pointed edges. In thisstate, since a core part of the lead comes into electrical contact withthe pointed edges, a distal end of the lead can be connected with thelead terminal electrically.

In order to fix the so-constructed lead terminal on the substrate, thepin part of the lead terminal is firstly inserted into an attachmenthole formed in the substrate, so that the fit part abuts on a peripheryof the attachment hole. Thereafter, the pin part projecting from theback surface of the substrate is soldered with a circuit on thesubstrate. In this way, the attachment of the conventional lead terminalto the substrate can be completed.

Thus, in the conventional lead terminal, the above insertion of the leadinto the V-shaped groove facilitates the electrical connection of thelead with the circuit in the substrate.

Beside the above-mentioned terminal structure, there is also knownanother terminal structure which can be attached to the substrate bymeans except soldering. This terminal structure is provided by bendingan elongated conductive metal plate, The terminal structure comprises acircuit-contact part which is to be fitted to the insulating substrateso as to expose itself on one side of the insulating substrate and aconnecting part which penetrates through the substrate and projects onanother side thereof. The insulating substrate is provided, on theformer side, with a circuit printed thereon and electrically connectedwith the terminal structure. In assembly, by connecting the connectingpart of the terminal structure with a mating terminal, the circuit onthe insulating substrate can be connected with the mating terminal.

Now, providing that the lead is inserted into the above-mentioned leadterminal on pressure in the former case or that the terminal structureis connected with the mating terminal in the latter case, any force forthe substrate will be applied on the lead terminal or the terminalstructure. Consequently, the pin part soldered with the substrate maybecome rickety in the former case, while the circuit-contact part may belifted from the insulating substrate thereby to cause the terminalstructure to be clattered in the latter case.

In the former case, even if the lead terminal totters against thesubstrate in this way, no problem would be caused because the lead hasonly to be fitted into the V-shaped groove. To the contrary, if thecircuit-contact part of the latter terminal is raised from theinsulating substrate unsteadily, it would be caused a problem thatcracks are produced in the circuit formed on the circuit-contact part,so that the circuit is broken down.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a terminaland a terminal attachment structure which is capable of preventing theterminal from tottering against a circuit assembly.

The object of the present invention described above can be accomplishedby a terminal attachment structure comprising, in combination:

a circuit assembly consisting of an insulating substrate and a circuitprinted and formed on a surface of the insulating substrate;

a terminal attached to the circuit assembly and connected with thecircuit electrically;

wherein the terminal comprising, under its attached condition to thecircuit assembly:

a circuit-contact part interposed between the surface of the insulatingsubstrate and the circuit to come in contact with the circuit;

a connecting part formed to project from the other surface of theinsulating substrate and connected with a mating terminal; and

a cradle part arranged between the circuit-contact part and theconnecting part for receiving a force applied on the connecting parttoward the insulating substrate thereby to prevent the terminal fromclattering with respect to the insulating substrate.

With the arrangement mentioned above, when a force directing theinsulating substrate is applied on the connecting part, the cradle partoperates to receive the force. Accordingly, since the force is nottransmitted to the circuit-contact part, it does not rise from theinsulating substrate, so that tottering of the terminal against thecircuit assembly can be prevented.

Preferably, the connecting part may be arranged to penetrate theinsulating substrate from the surface to the other surface, while thecradle part may be constituted by a projection which is formed so as toproject from a portion of the connecting part toward the surface of theinsulating substrate and which engages with the insulating substrate.

In this case, when the force directing the insulating substrate isapplied on the connecting part, the force is countered by an engagementof the projection with the insulating substrate. Thus, also in thiscase, since no force is applied on the circuit-contact part, it does notrise from the insulating substrate, so that tottering of the terminalagainst the circuit assembly can be prevented.

More preferably, the circuit-contact part of the terminal is provided,at a leading end thereof, with a press fit projection which is fittedinto the insulating substrate under pressure.

In this case, owing to fitting of the press fit projection at theleading end of the circuit-contact part into the insulating substrateunder pressure, it is possible to securely fix the terminal on theinsulating substrate in position without causing the tottering of theterminal against the insulating substrate.

In the present invention, preferably, the circuit assembly has anengagement recess formed on the surface so as to engage with theterminal while the circuit-contact part is exposed on the side of thesurface of the insulating substrate.

In this case, owing to the engagement of the engagement recess with theterminal, it is possible to attach the terminal to the circuit assemblyfirmly.

More preferably, the circuit assembly has an engagement groove formed soas to engage with the press fit projection of the terminal.

Also in this case, it is possible to attach the terminal to the circuitassembly firmly.

Furthermore, according to the present invention, it is also provided aterminal for electrically connecting a circuit of a circuit assemblywith a mating terminal, the terminal comprising:

a circuit-contact part for the circuit of the circuit assembly, thecircuit-contact part being shaped in form of an elongated plate;

a cradle part joined to one end of the circuit-contact part; and

a connecting part for the mating terminal, which is connected with thecradle part, the connecting part being shaped in form of an elongatedplate.

Preferably, the cradle part may comprise a projection.

In the present invention, more preferably, the circuit-contact part ofthe terminal is provided, at a leading end thereof, with a press fitprojection.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims taken in conjunction with the accompany drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a terminal attachment structureconsisting of a terminal and a circuit assembly in accordance with afirst embodiment of the present invention;

FIG. 2 is a perspective view showing a condition before the terminal isattached to the circuit body in the first embodiment;

FIG. 3 is a perspective view showing a condition after the terminal isattached to the insulating substrate in the first embodiment;

FIG. 4 is a perspective view of a terminal attachment structure of theterminal to the circuit body in accordance with a second embodiment ofthe present invention;

FIG. 5 is a perspective view of the terminal of the second embodiment;and

FIGS. 6A to 6C show step of attaching the terminal of the secondembodiment to the circuit body, wherein FIG. 6A is a cross sectionalview showing a condition before the terminal is attached to theinsulating substrate; FIG. 6B is a cross sectional view showing acondition that the terminal is attached to the insulating substrate; andFIG. 6C is a cross sectional view showing a condition that a circuit isformed on the insulating substrate having the terminal attached thereto.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the present invention will be described with reference tothe drawings. In figures, FIGS. 1, 2 and 3 show a terminal 20 and itsattachment structure to a circuit assembly 21, in accordance with thefirst embodiment of the invention.

The circuit assembly 21 to which the terminal 20 of the embodiment is tobe attached is constituted by an insulating substrate 22 on which acircuit 23 is printed and formed. Note, the insulating substrate 22 ismade of plastic material or the like, while the circuit 23 is composedof conductive paste or the like. As shown in FIG. 1, the terminal 20 ofthe embodiment comprises a circuit-contact part 25 interposed between asurface 24 of the insulating substrate 22 and the circuit 23 so as tocome in contact with the circuit 23, a connecting part 27 arranged so asto project from the opposite surface 26 of the insulating substrate 22and connect with a not-shown mating terminal, and a cradle part 28disposed between the circuit-contact part 25 and the connecting part 27to receive a force applied on the substrate 22 and prevent clattering ofthe terminal 20 with respect to the substrate 22. The cradle part 28consists of a cradle plate element 29 and a joint plate element 30 forconnecting the cradle plate element 29 with the circuit-contact part 25.The cradle plate element 29 is formed in parallel with thecircuit-contact part 25 and disposed on the side of the surface 26 ofthe substrate 22. Therefore, the insulating substrate 22 is interposedbetween the circuit-contact part 25 and the cradle plate element 29.

The terminal 20 is produced by bending an elongated conductive platematerial, providing a substantial U-shaped configuration by thecircuit-contact part 25, the joint plate element 30 and the cradle plateelement 29. The end portion of the cradle plate element 29 is bent atright angle to provide the connecting part 27. Furthermore, the endportion of the circuit-contact part 25 is also bent at right angle inthe direction of the connecting part 27 thereby providing a press fitprojection 31.

On the other hand, the circuit assembly 21 is provided, adjacent anouter edge thereof, with a fit or engagement recess 32 for engagementwith the circuit-contact part 25 on condition that exposing surface 25 athereof is exposed. In addition, at the end of the fit recess 32, apress fit or engagement groove 33 is formed for engagement with thepress fit projection 31.

We now describe steps of attaching the terminal 20 to the insulatingsubstrate 22 in order to electrically connect the circuit 23 of thecircuit assembly 21 with the terminal 20.

After opposing the terminal 20 laterally to the insulating substrate 22as shown in FIG. 2, the circuit-contact part 25 is fitted into theengagement recess 32 on the surface 24 of the substrate 22. Then, thecradle plate element 29 is also abutted against the other surface 26, sothat the joint plate element 30 comes into contact with the side face ofthe insulating substrate 22, as shown in FIG. 3. Under such a condition,the side edge portion of the substrate 22 is interposed between thecircuit-contact part 25 and the cradle plate element 29. Note that, thepress fit projection 31 is inserted into the press fit groove 33 underpressure, simultaneously,.

After the engagement of the terminal 20 with the circuit assembly 21 ishas been completed, the circuit 23 is printed on the surface 24 of theinsulating substrate 22, as shown in FIG. 1. Simultaneously, the circuit23 is also formed on an exposing face 25 a of the circuit-contact part25. In this way, the terminal 20 is electrically connected with thecircuit 23.

The so-constructed terminal 20 operates as follows.

When the terminal 20 is subjected to a force which presses theconnecting part 27 toward the insulating substrate 22, the cradle plateelement 29 comes into contact with the other surface 26 of theinsulating substrate 22. Thus, since the force is not transmitted to thecircuit-contact part 25 directly, it would not be lifted from theengagement recess 32, so that clattering of the part 25 does not occur.In addition, owing to contact of the cradle plate element 20 with theinsulating substrate 22, it is possible to prevent the terminal 20 fromclattering with respect to the insulating substrate 22.

In this way, even if applying force directing to the insulatingsubstrate 22 on the connecting part 27, the force is not exerted on thecircuit-contact part 25 due to a contact of the cradle plate element 29with the other surface 26 of the insulating substrate 22, so that thepart 25 is nor raised from the engagement recess 32. Therefore, since noforce is applied on the circuit 23 formed on the surface 24 of theinsulating substrate 22, any crack is not generated in the circuit 23,so that the damage thereon can be prevented certainly.

In addition, since the press fit projection 31 at the end of thecircuit-contact part 25 is fitted into the press fit groove 33 of theinsulating substrate 22 under pressure, the arrangement also makes itpossible to prevent the terminal 20 from clattering against theinsulating substrate 22.

The second embodiment of the invention will be described hereinafterwith reference to FIGS. 4, 5 and 6. Note, in the embodiment, elementssimilar to those of the first embodiment are indicated with the samereference numerals, respectively and repetitive descriptions aredeleted.

A terminal 35 of the embodiment comprises a connecting part 36penetrating the insulating substrate 22 from the side of the surface 24to the other side of the surface 26 and a cradle part 37 consisting of aprojection 38 projecting from a portion of the part 36, which isembedded in the insulating substrate 22, toward the surface 24.

Thus, it will be understood that the terminal 35 of the embodiment isattached to the interior side of the circuit assembly 21 so as topenetrate it while the terminal 20 of the first embodiment is attachedto the exterior side of the circuit assembly 21.

As shown in FIGS. 4 and 5, the circuit-contact part 25 of the terminal35 is partially bent at right angle, providing the connecting part 36.The connecting part 36 consists of a wide portion having a width equalto that of the circuit-contact part 25 and a narrow portion integratedwith the wide portion. The projection 38 is formed on the wide portionof the connecting part 36 to project toward the circuit-contact part 25.

While, as shown in FIG. 6A, the insulating substrate 22 is provided, onthe side of the surface 24, with an engagement recess 39 and a press fitgroove 33 which is arranged on one side of the engagement recess 39. Onthe other side of the engagement recess 33, a through hole 40 is formedso as to penetrate the insulating substrate 22. In the through hole 40,a step part 41 is formed to have an engagement wall 42 opposing thesurface 26. Under condition that the terminal 35 is fitted into therecess 39, the projection 38 engages with the engagement wall 42.

In order to attach the terminal 35 to the circuit assembly 21, theconnecting part 36 is inserted into the through hole 40 and thecircuit-contact part 25 is fitted into the engagement recess 39 whilethe press fit projection 31 is inserted into the press fit groove 31, asshown in FIG. 6A. During fitting of the terminal 35, the projection 38is bent due to its abutment with an edge of the through hole 40 in amoment.

Thereafter, when the projection 38 surmounts the edge of the throughhole 40, the projection 38 returns to its original position in the hole40, as shown in FIG. 6B. In this state, the leading end of theprojection 38 abuts on the engagement wall 42.

Next, as shown in FIG. 6C, the circuit 23 is printed on the surface 24of the insulating substrate 22, including the surface 25 a of thecircuit-contact part 25. In this way, the terminal 35 can be attached tothe circuit assembly 21 while being electrically connected with thecircuit 23.

The terminal 35 of the embodiment operates as follows.

When the terminal 35 is subjected to a force which presses theconnecting part 36 toward the insulating substrate 22, the projection 38comes into contact with the engagement wall 42. Thus, since the force isnot transmitted to the circuit-contact part 25 directly, it would not belifted from the engagement recess 39, so that clattering of the part 25does not occur, whereby the circuit 29 can be protected without beingdamaged.

Finally, it will be understood by those skilled in the art that theforegoing description is one of preferred embodiments of the disclosedterminal attachment structure, and that various changes andmodifications may be made to the present invention without departingfrom the spirit and scope thereof.

What is claimed is:
 1. A terminal attachment structure comprising: acircuit assembly comprising an insulated substrate and a circuit printedand formed on a surface of the insulating substrate; a terminal attachedto the circuit assembly and connected with the circuit electrically, theterminal comprising: a circuit-contact part interposed between thesurface of the insulating substrate and the circuit to come in contactwith the circuit; a connecting part projecting from a back surface ofsaid insulating substrate, opposite to the surface of the insulatingsubstrate, and connectable with a mating terminal, whereby saidconnecting part penetrates said insulating substrate from the surface tothe back surface; and a cradle part arranged between the circuit-contactpart and the connecting part for receiving a force applied on theconnecting part toward the insulating substrate thereby to prevent theterminal from clattering with respect to the insulating substrate, thecradle part including a projection which projects from a portion of saidconnecting part toward the surface of said insulating substrate andwhich engages with said insulating substrate.
 2. A terminal attachmentstructure according to claim 1, wherein the circuit-contact part of saidterminal is provided, at a leading end thereof, with a press fitprojection fitted into said insulating substrate under pressure.
 3. Aterminal attachment structure according to claim 2, wherein the circuitassembly is provided, on the surface of the insulating substrate, withan engagement recess for engagement with the terminal, which is soformed as to expose the circuit-contact part of the terminal on thesurface of the insulating substrate.
 4. A terminal attachment structureaccording to claim 3, wherein the circuit assembly has an engagementgroove formed so as to engage with the press fit projection of theterminal.
 5. A terminal for electrically connecting a circuit of acircuit assembly with a mating terminal, said terminal comprising: acircuit-contact part for contacting said circuit of said circuitassembly, said circuit-contact part being shaped in the form of anelongated plate; a cradle part joined to one end of said circuit-contactplate, said cradle part including a projection; and a connecting partconnectable with said mating terminal, said connecting part is connectedto said cradle part, said connecting part being shaped in the form of anelongated plate.
 6. A terminal according to claim 5, wherein saidcircuit-contact part of said terminal is provided, at a leading endthereof, with a press fit projection.